1. Field of the Invention
The disclosed embodiments of the present invention relate to impedance adjustment, and more particularly, to an adjustable impedance circuit capable of realizing differential-mode impedance matching as well as common-mode impedance matching, and a related impedance setting method.
2. Description of the Prior Art
Most input/output (I/O) interfaces define differential-mode impedances, where resistance array self-calibration is commonly used for realizing the differential-mode impedance matching. In different fabrication processes, the resistance array self-calibration may obtain corresponding corner correction via a calibration circuit to meet the differential-mode impedance requirements for an I/O interface. Regarding an I/O interface which defines both differential-mode impedance and common-mode impedance, as the differential-mode impedance and the common-mode impedance have different definitions and impedance values, the calibration circuit is required to be designed correspondingly. For example, individual calibration circuits are needed to calibrate the differential-mode impedance and the common-mode impedance, respectively. Additional calibration circuits are needed, and power consumption and/or calibration time are increased thereof.